Electroluminescent capacitorphosphor lamp



APII 7, 1959 l H. A. MICHLIN 2,881,344

ELECTROLUMINESCENT CAPACITOR-PHOSPHOR LAMP Filed Sept. 28, 1955 FIG! United States Patent O ELECTROLUMINESCENT CAPACITOR- PHOSPHOR LAMP Hyman A. Michlin, New York, N.Y.

Application September 28, 1956, Serial No. 612,771

19 Claims. (Cl. 313-108) This invention relates to electrolurninescent phosphors, that is phosphors which luminesce when placed in an electric field; and in particular to electroluminescent capacitor-phosphor particles, to electroluminescent lamps made therewith, and to methods for making said electroluminescent lamps.

An electroluminescent lamp and capacitor-phosphor particles is a light-emitting device made after the manner of a flat plate capacitor, except that one of the plates is made of transparent conducting material such as tin oxide and the space between the plates is occupied by a thin layer of dielectric material in which there is a phosphor such as zinc sulphide, or, by a thin layer of powdered phosphor particles, such as zinc sulphide with manganese carbonate, pressed together. The intensity of emitted light from the said phosphors increased with the increase and decrease of voltage and with higher frequencies so that alternating, pulsating or otherwise varying current in high voltages and high frequencies are most effective.

At the present state of the art phosphor particles having conductive coat crystal contact are found to luminesce more efficiently, one form of which is disclosed in Patent No. 2,755,406. The said patent discloses metalcrystal contact phosphor particles in a compressed layer having a mixture of partly metal coated and uncoated phosphor particles, with the limitation that the quantity of the coated phosphor particles with respect to the quantity of the uncoated phosphor particles be small so as to prevent short-circuiting and arcing; and, due to the disoriented and haphazard arrangement of the partly metal coated parts of the phosphor particles with respect to each other and to the direction of the electric field effected between the electrode layers, there is the further limitation of inefficient electric field application by means of the metal coat to their respective phosphor particles. Another limitation in the present state of the art is the difculty of high frequency application of electric fields over a large area of large units.

One object of this invention is to increase the relative quantity of capacitor-phosphor particles in a phosphor layer so that all or nearly all of the phosphor particles in a phosphor layer are capacitor-phosphor particles.

Another object of the invention is to provide a method and means to reduce short-circuiting or arcing in a layer of capacitor-phosphor particles.

Another object of the invention is to provide capacitorphosphor particles capable of producing electric oscillations and applying said oscillations to the phosphor particles.

Another object is to provide a phosphor layer having therein oriented capacitor-phosphor particles in series capacitance.

Another object is to produce an electroluminescent lamp with plural capacitor-phosphor particle layers with reduced possibility of electrical breakdown.

Other features, objects and advantages of the invention '2,881,344 Patented Apr. 7, 1959 2 will be apparent from the following specification, taken in connection with the accompanying drawings in which:

Figure 1 is a cross-sectional view of one embodiment of the invention; Figures 2, 3 and 4 are schematic representations of electroluminescent phosphor layers; and Figure 5 is a schematic representation of capacitor-phosphor particles.

The electroluminescent lamp disclosed in Patent No. 2,75 5,406 is deemed part of this disclosure.

Conductive coat-crystal contact and conductive coatcrystal near contact capacitor-phosphor particles are schematically illustrated in Figure 5; and the producing of them is preferably done with metal coats deposited in vapor form in vacuum, and, to be light-transmitting. Further, where the metal applied have magnetic properties such as iron, nickel and etc., an unbalance of said particles by magnetic means can be eected.

The capacitor-phosphor particle schematically illustrated in Fig. 5-A can be made, for example, by coating an area less than half of the surface of the phosphor crystal 8, for example Zinc sulphate with manganese carbonate, with a thin metal film 9, for example silver, and preferably one micron or less thick to effect a conductive coat-crystal contact therewith. A very thin film of low conductance of low resistance substance 10, for example tellurium, is then coated over and a little beyond said thin metal film 9. Unbalanced capacitor-phosphor particles are effected by the weight of the applied coats, which particles can be, for example, settled through a liquid so that the coated parts are face down. After the liquid is removed, a very thin metal film 9, for example silver, and preferably one micron or less thick, is then coated on the uncoated part of each of said capacitor-phosphor particle and in electric contact with the film 10. The coated phosphor particles are then, preferably, ball milled so 'as to remove excess film and still maintain their respective unbalanced condition and capacitor-phosphor structure so as to act as an oscillator on excitation thereof. Other low resistance or low conductance substances are germanium and the carbon used in incandescent lamps. Fig. 5-F schematically illustrates an unbalanced capacitorphosphor particle where the second coat of silver is a film of aluminum 11 having a film of tellurium 12 coated thereon and not in contact with the aluminum coat 11, and a film of tellurium 10 coated over the aluminum coat 11 and not in contact with the tellurium coat 12.

The capacitor-phosphor particles schematically illustrated in Figures 5-B and S-C can be made, for example, by covering an area less than half of the surface of the phosphor crystal 8, for example zinc sulphate with manganese carbonate, with a thin metal lm 9, for example silver, and preferably one micron or less thick, to effect a conductive coat-crystal contact therewith. The result is the unbalanced capacitor-phosphor particles schematically illustrated in Fig; S-C. The said capacitorphosphor particles act in a capacitive function in example schematically illustrated in Fig. Z-C and in Fig. 4 where such capacitor-phosphor particles are aligned to coact with each other in forming capacitor structures in series capacitances with the phosphor the principal dielectric in the capacitor Structure in series capacitances in Fig. 4; and with the phosphor coacting with the dielectric layer the principal dielectric in the capacitor structural function in series capacitances in Fig. 2-C.

The said unbalanced capacitor-phosphor particles of Fig. 5-C can be, for example, settled through a liquid so that the coated parts are face down. After the liquid is removed a very thin and light metal film 11, for example aluminum, and preferably one micron or less thick, is coated over part of the uncoated surface of said unbalanced capacitor-phosphor particles with an open area beice .applied coats.

aange-i4 tween the metal coats 9 and 11 to etect a high electric resistance therebetween. Unbalanced capacitor-phosphor particles are effected by the difference in weight ofthe By applying a very thin lilm of dielectric 13 of high strength of one micron or less thick directly to the capacitor-phosphor particles schematically illustrated in Fig. S-B, the capacitor-phosphor particle schematically illustrated in Fig. S-E can be formed with reduced possibility of electrical breakdown.

Another example of capacitor-phosphor particle is schematically illustrated in Figure S-D wherein phosphor particle 8, for example zinc sulphate with manganese carbonate, is coated over with dielectric 13, and a separate metal lm of silver 9 is applied over one part of the surface of the dielectric coating 13 and another separate metal lm of aluminum 11 is applied over an opposite part of the surface of the dielectric coating 13.

The phosphor layers schematically illustrated in Figs. 2-A, B and C are produced by separately placing unbalanced capacitor-phosphor particles, for example those schematically illustrated in Figs. -A, B and C, respectively, in a melt of dielectric material 14 of about 0.004 inch thick, an example of which is disclosed in Patent No. 2,733,367. Where the unbalance of the capacitor-phosphor particles is due to magnetic conditions of the metal in crystal contact then, obviously, the capacitor-phosphor particles can be magnetically aligned in proper orientation to effect capacitance in line with electric field. Where the unbalance is by reason of diiference in weight, then the layer can be agitated so as to align the capacitorphosphor particles by gravity to effect capacitance in line with electric lield. The Whole of the above is placed between the conductive coating 2 and metal backing 4 in the lamp structure schematically illustrated in Fig. l. Further, examples of unbalanced capacitor-phosphor particles which can be used are schematically illustrated in Figures S-E and F. Further the above examples are merely by way of illustration and is not intended to be restrictive.

The capacitor-phosphor layer example schematically illustrated in Figure 2 is produced by placing a metal conductive coating 2 on glass 1, for example as illustrated in Fig. 1, in a tank of liquid, and settling the unbalanced capacitor-phosphor particles to about 0.004 inch thick. The unbalanced capacitor-phosphor particles, preferably have a high dielectric over-all coating, an example of which is schematically illustrated in Fig. 5-E so as to increase dielectric strength of the capacitor-phosphor layer when same is aligned in series capacitance on the conductive coat 2. The liquid s then removed; and a metal backing layer 4 is placed on the aligned capacitor-phosphor particles; and the whole is then compressed and placed in lamp structure as is schematically illustrated in Figure l.

The plurality of capacitor-phosphor layers schematically illustrated in Figure 4, as an example, is of two capacitorphosphor particles layers, each 0.003 inch thick and separated by a Very thin light transmitting dielectric layer of about 0.002 inch thick, an example of which is disclosed in Patent No. 2,733,367, supra; and the whole is compressed and placed in lamp structure as is schematically illustrated in Figure l. It is to be understood that different capacitor-phosphor particles can be used in the above examples and, therefore, is not intended to be restrictive; and, further, that each capacitor-phosphor particle layer can be one capacitor-phosphor particle thick.

Figure l schematically illustrates an electroluminescent lamp wherein the glass plate 1 has the `light-transmitting, electrically-conductive-coating 2 thereon, over which a layer 3 of compressed electroluminescent capacitor-phosphor particles or a layer of capacitor-phosphor particles in dielectric, with metal backing layer 4 thereover. A mica piece 5 is placed over the metal layer 4, and extends beyond the edges thereof to protect the phosphor layer 3. A layer 6 of plastic or ceramic material encloses the back of the device and is sealedto the glass plate 1 around the edges of the latter. Alternating, varying or pulsating current source 7 is of high electric field of the order of 10 kv. to 20 kv. and of low frequency of the order of 60 cycles.

The capacitor-phosphor particles within the low frequency electric elds by reason of its small resistancecapacitance coupling, produces an oscillation of higher frequency; and by reason of the conductive coat-crystal contact or near contact there is effected a contact application of electric fields to produce electroluminescence.

While the present invention has been described with reference to particular embodiments thereof, it Will be understood that numerous modifications may be made by those skiled in the art without actually departing from the invention. Therefore, I aim in the appended claims to cover all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.

I claim:

1. Electroluminescent capacitor-phosphor crystals, each said phosphor crystal having a plurality of separated conductive coats each in a separate part thereof and arranged in capacitor structure.

2. The electroluminescent capacitor-phosphor crystals of claim 1 in which the conductive coats are of metal.

3. The electroluminescent phosphor crystal of claim 1 in which at least one part thereof is of such material and quantity as to be capable of being affected by a force applied thereto through space so as to constrainably position the phosphor crystal in a predetermined direction when such outside force is applied.

4. The electroluminescent phosphor crystals of claim 3 in which at least one part of each of the phosphor crystals is of such weight as to position the phosphor crystals in a predetermined direction when subjected to gravitational force.

5. The electroluminescent phosphor crystals of claim 3 in which at least one part of each of the phosphor crystals is of such material as to position the phosphor crystals in a predetermined direction when subjected to magnetic force.

6. The electroluminescent capacitor-phosphor crystals of claim 1 in which there is electrical connection of less conductance than the conductive coats between the conductive coats in the capacitance structure arrangement so as to effect an oscillation circuit as a part of the phosphor crystal.

7. The electroluminescent capacitor-phosphor crystals of claim 2 in which there is electrical connection of less conductance than the conductive coats between the conductive coats in the capacitance structure arrangement so as to eifect an oscillation circuit as a part of the phosphor crystal.

8. The electroluminescent capacitor-phosphor crystals of claim 3 in which there is electrical connection of less conductance than the conductive coats between the conductive coats in the capacitance structure arrangement so as to effect an oscillation circuit as a part of the phosphor crystal.

9. The electroluminescent capacitor-phosphor crystals of claim 4 in which there is electrical connection of less conductance than the conductive coats between the conductive coats in the capacitance structure arrangement so as to effect an oscillation circuit as a part of the phosphor crystal.

10. The electroluminescent capacitor-phosphor crystals of claim 5 in which there is electrical connection of less conductance than the conductive coats between the conductive coats in the capacitance structure arrangement so as to effect an oscillation circuit as a part of the phosphor crystal.

11. The capacitor-phosphor crystal of claim 1 and dielectric covering overall.

l2. The capacitor-phosphor crystal of claim 6 and a dielectric covering overall.

13. Capacitor-phosphor crystal comprising a phosphor crystal, a dielectric overall covering the phosphor crystal, a plurality of separate conductive layers over the dielectric covering, said separate conductive layers arranged in a capacitor structure.

14. Capacitor-phosphor crystal as an oscillation circuit comprising the capacitor-phosphor crystal of claim 13 and electrical connection between each of the separate conductive layers of each phospphor crystal with a material of less conductivity than the conductive layers so as to form an oscillation circuit.

l5. A phosphor layer for use in an electroluminescent cell comprising at least one layer of phosphor particles, each of said phosphor particles having a conductive coat in contact With a part thereof, each of said phosphor particles aligned in series capacitances and in a common direction with respect to the part thereof covered by the conductive coat, and each of said conductive coats separated from the other conductive coats.

16. A phosphor layer for use in an electroluminescent cell comprising at least one layer of phosphor crystals, each phosphor crystal having separated conductive coats in contact and arranged in capacitor structure, each of the said capacitor structures aligned in series capacitances and in one direction common to their capacitive function, and the conductive coats of each capacitor structure separated from the conductive coats of the other capacitor structures.

17. A phosphor layer for use in an electric eld frequency operated electroluminescent cell, the phosphor layer comprising a plurality of capacitor phosphor crystals, each of said capacitor phosphor crystals having a plurality of electrically separated conductive layers in a capacitor structure; each said capacitor structure arranged electrically separate and in a common direction to their capacitive function in line with the application of electric field frequencies of the electroluminescent cell thereby producing electroluminescence.

18. The phosphor layer for use in an electric eld frequency operated electroluminescent cell, the phosphor layer comprising a plurality of capacitor phosphor crystals, each of said capacitor phosphor crystals having a plurality of separated conductive layers in a capacitor structure, said conductive layers in each capacitor structure electrically connected by substances of less conductance than the conductance of the conductive layers to effect a high resonant frequency electric field oscillation circuit thereby, said resonant frequency of electric elds harmonic to said frequency of electric fields; each said capacitor structure arranged separate and in a common direction in line with their capacitive function in line with the application of electric fields thereby producing electroluminescence.

19. The phosphor layer for use in an electric eld frequency operated electroluminescent cell, the phosphor layer comprising a plurality of capacity phosphor crystals, each of said capacitor phosphor crystals having a plurality of separated conductive layers in a capacitor structure, said conductive layers in each capacitor struc` ture electrically connected by substances of less conductance than the conductance of the conductive layers to eiect a resonant frequency electric field oscillation circuit thereby, said resonant frequency of electric elds harmonic to said frequency of electric fields; each said capacitor structure arranged separate and in a common direction in line with their capacitive function and in a series capacitance with at least one other capacitor structure in line with the application of the electric elds thereby producing electroluminescence.

References Cited in the tile of this patent UNITED STATES PATENTS 2,610,386 Saslaw Sept. 16, 1952 2,755,406 Burns July 17, 1956 2,793,420 Johnston et al May 28, 1957 2,809,316 .leges Oct. 8, 1957 2,821,646 Walker Jan. 28, 1958 In Inte Electrolumnes patentee was rendered Ma Ocz'al Gazete, April 17, 1.962.]

Notice of Adverse rference No. 91,199 invo Cent capacltor- I'. 14, 1962, as to clalms l and`l1.

Decision in Interference gment advers Michlin, e to the Notice of Adverse Decision in Interference In Interference N o. 91,199 involving Patent N o. 2,881,344, H. A. Michlin, Electrolumnescent capacitor-phosphor lamp, final judgment adverse to the patentes Was rendered Mar. 14, 1962, a

s to claims 1 and 11. [Oficial Gazete,Ap1z'ZZ7,1962.] 

1. ELECTROLUMINESCENT CAPACITOR-PHOSPHOR CRYSTALS, EACH SAID PHOSPHOR CRYSTAL HAVING A PLURALITY OF SEPARATED CONDUCTIVE COATS EACH IN A SEPARATE PART THEREOF AND ARRANGED IN CAPACITOR STRUCTURE. 